The present invention relates to a system for an automatic charging and/or discharging of X-ray film sheets into and/or from cassettes of different formats; the cassettes are of a flat rectangular configuration and are provided on one of its major walls with a label carrying information in the form of a bar code about the cassette and/or the film sheet contained in the cassette. The system also includes an apparatus for the automatic charging and/or discharging of a film sheet into a cassette, the apparatus including a conventional electrooptical bar code reader.
X-ray film sheet charging and discharging apparatuses of this kind are known for example from the German patent No. 3,232,148. A disadvantage of this prior art apparatus is a relatively complicated determination of the format of a cassette to be inserted and, consequently the selection of a film sheet to be reinserted into the cassette is also relatively complicated.
From the European patent application No. 00 79 557 it is known to provide storing foils or X-ray films with bar codes or magnetic codes located in the range of an openable illumination window of a cassette so as to enable an automatic reading information concerning the storage foil. In addition, from the German Patent No. 3,147,956 it is also known how to apply an erasable bar code or magnetic code or an electrostatic code on the cover of an X-ray cassette in order to check an intended multiple exposure or illumination.
However, if it is desired to employ such prior art bar codes for information about the cassette or film sheet format and to read the information in an automatically operating charging and/or discharging apparatus, a difficulty is encountered when cassettes of completely different formats are to be inserted into the charging and discharging apparatus. Cassettes of large format during the advance into the intake compartment are due to their size guided with sufficient accuracy in the prescribed feeding direction so as to reliably reach their working position in which the automatic bar code reader can read the code without problems. However the smaller is an inserted cassette the more frequently a possibility occurs that during the transport the cassette becomes misaligned relative to the feeding direction and consequently when reaching its end position in which it is realigned there is the probability that in the case of small format cassettes only a part of the bar code passes within the range of the code reader,resulting in incorrect reading of the coded information and a malfunction in the automatic selection of a film to be inserted in the cassette.